1. Field of the Invention
The present invention generally relates to a recording apparatus. More specifically, the present invention is directed to a printer head, or a printer having a recording head positioned opposite to a printing medium such as a printing paper, also to and a recording solution jetting unit for jetting a recording solution such as a vaporizable dye to this printing medium.
2. Description of the Related Art
Very recently, various needs such as monochromatic recording needs and also color hard copying needs are increased in video cameras, televisions, and image recording fields, for instance, computer graphics. To satisfy these needs, various color hard copy systems have been proposed, for example, the sublimation type thermoelectric system, the melting thermoelectric system, the ink jet system, the electronic photographic system, and the thermal developing silver halide system.
The above-described various color hard copy systems are mainly classified into the dye diffusion thermoelectric system (sublimation type thermoelectric system) and the ink jet system, which may function as a color hard copy type apparatus, capable of easily producing images with high image qualities.
In this dye diffusion thermoelectric system among these recording systems, and ink sheet and a printing medium (printing paper) are made in close contact with each other under certain pressure, a thermal recording head positioned above the ink sheet may apply heat to this ink sheet in response to image information, and a transferring dye is thermally transferred from the ink sheet to a dye accepting layer in response to this heat application. The ink sheet is coated with an ink layer made by distributing a transferring dye (will also be referred to a xe2x80x9crecording materialxe2x80x9d hereinafter) with high density in a properly-selected binder resin. A dye-coated resin for accepting the transferred dye is coated on the printing medium.
A so-called xe2x80x9cthermoelectric systemxe2x80x9d is featured by having instantaneous printing operation, and capable of producing full images with high image qualities substantially equal to those of silver halide color pictures. In this thermoelectric system, for instance, the above-described operation is repeatedly performed as to color image signals for yellow, magenta, and cyan, corresponding to the three primary colors used in the subtraction color mixture.
FIG. 1 schematically shows a front view of a major portion of a printer with employment of such a thermoelectric system. In this printer, a thermosensible recording head (simply will be referred to as a xe2x80x9cthermal headxe2x80x9d hereinafter) 70 is positioned opposite to a platen roller 71. Between these thermal head 70 and platen roller 71, both an ink sheet 72 made of an ink layer 72a formed on a base film 72b, and a recording paper (printing medium) 20 made of a dye-coated resin layer (dye accepting layer) 20a formed on a paper 20b are traveled with being depressed against the thermal head 70 by the platen roller 71 under such a condition that the ink sheet 72 is sandwiched with the recording paper 20.
Then, the ink (transferring dye) contained in the ink layer 72a selectively heated by the thermal head 70 is transferred in a dot shape to the dye-coated resign layer 20a of the printing medium 20, so that the thermoelectric recording operation is carried out. In general, as to such a thermoelectric recording system, the line system and the serial system are employed. In the line system, a longitudinal-shaped thermal head is positioned perpendicular to a travel direction of a recording paper and is fixedly arranged. In the serial system, a thermal head is reciprocated along a direction perpendicular to a travel direction of a recording paper.
FIG. 2 schematically indicates a plan view of an adjoining portion of a transfer unit of the thermal head 70.
A ceramics substrate 73 is fixed to a portion above a heat radiation plate (not shown) made of a high heat conductivity material (for instance, aluminium).
A glaze layer 74 is formed at one edge portion above the ceramics substrate 73 while a tip portion thereof is left. A large number of heat emitting layers (made of polysilicon layer (Pxe2x80x94Si), or a metal having a high resistance) 75 are arranged in such a manner that these heat emitting layers 75 ride the glaze layer 74. Separate electrodes 76 and a common electrode 77 are arranged on the ceramics substrate 73 by being connected to the heat emitting layer 75 in such a manner that these separate electrodes 76 and the common electrode 77 are positioned opposite to each other on each of the heat emitting layer 75 at a summit of the glaze layer 74 while maintaining a small space.
The separate electrodes 76 are elongated near the edge portion of the ceramics substrate 73, and the common electrode 77 is elongated up to the edge portion on the side of the glaze layer 74. The ceramics substrate 73 is covered with an anti-wearing protection layer with involving the heat emitting layer 75 on the separate electrodes 76 and the glaze layer 74, and on the common electrode 77 while the tip portion of the separate electrode 76 is left. It should be noted that this protection layer is omitted from FIG. 2.
However, this system owns such serious drawbacks. That is, a large amount of wastes are produced which are caused by disposing the ink sheets, and the running cost is increased. The serious drawbacks impede the utilization of this system. This drawback is also applied to the melting thermoelectric system.
Additionally, in a full color recording operation, there are some possibilities that the specific color ink which has been once adhered to the recording paper is conversely transferred to other color ink sheets, resulting in color mixtures. As a result, there is such a risk that dirty images are recorded.
Although the thermal developing silver halide system may provide the high image quality, the running cost is increased and also the manufacturing cost of the recording apparatus is increased because the exclusively-used printing paper and the disposable ribbons or the disposable sheets are used.
On the other hand, the ink jet system is described in, for example, Japanese Examined Patent Publication No. 61-59911 published in 1986 and Japanese Examined Patent Publication No. 5-217 published in 1993. In response to the image information, the recording ink droplets are jetted from the nozzles formed in the recording head so as to be adhered to the recording member for the image recording operation by way of the electrostatic attracting system, the continuous vibration generating system (piezoelectric system), and the thermal system (bubble jet system).
As a result, the image transfer operation can be done by using normal paper, and substantially no waste is disposed in such a case that the ink ribbon is used. Thus, the low running cost can be realized. Currently, in particular, since the color images can be simply outputted by the thermal system, this thermal system (bubble jet system) is popularized.
However, in this ink jet system, it is basically difficult to achieve the density gradation within pixels. Thus, it is practically difficult to reproduce such a high-quality image within short time, which may be obtained by way of the dye diffusion thermoelectric system. This image quality may be comparable to that of a silver halide picture.
In other words, in the conventional ink jet recording system, since one ink droplet forms one pixel, the gradation within one pixel can be hardly realized in view of a basic idea, so that the high-quality image cannot be formed. On the other hand, quasi-gradation representation by way of the dither method may be tried to be executed while utilizing high resolution achieved by the ink jetting system. However, this dither method could not produce images having image qualities equivalent to that made by the sublimation type thermoelectric system, but also the transfer speed by this dither method is considerably lowered.
Furthermore, although the electronic photographic system can achieve the low running cost and the high transfer speed, the manufacturing cost of this electronic photographic system is increased.
As previously described, there is no recording methods capable of satisfying all of the following needs, i.e., the image qualities, the running cost, the manufacturing cost of the recording apparatus, and the image transfer time.
To solve the above-described problems, the Inventors of the present invention have proposed the recording method and the recording apparatus in Japanese Laid-open Patent. Application No. 7-89107 corresponding to U.S. Pat. No. 5,592,208 patented on Jan. 7, 1997 entitled xe2x80x9cPRINTING METHOD AND A PRINTING APPARATUS FOR CARRYING OUT THE SAMExe2x80x9d. The recording apparatus of this prior patent filed by the Inventors includes the thermal medium (for instance, optical-heat converting member made of carbon fine particles and a binder, or a thin film of a nickel-cobalt alloy) for supporting/heating the recording material to which heat produced from the heating source (for example, semiconductor laser) is applied. This recording apparatus maintains the interval between the recording material and the printing medium in a range of 1 to 100 xcexcm. Then, the recording material is vaporized, or sublimated so as to be transferred to the printing medium by heating this recording material via the thermal medium.
Concretely speaking, in accordance with the thermoelectric recording method of this prior patent, the porous structure is formed in the recording material heating unit of the printer, and the surface area of the jetting unit (transfer unit) is increased by this porous structure, so that the recording fluid can be continuously supplied to the recording fluid heating unit by way the capillary phenomenon, and further can be held in this heating unit. Under this condition, the heat amount responding to the recording information is selectively applied by the heating means (for instance, laser light) so as to vaporize a portion of the recording fluid. An amount of recording material is transferred to the printing medium in the form of vapor, or fluid droplets. This recording material amount corresponds to the recording information responding to the electric image formed by the color video camera and the like. As a result, this electric image can be transferred to the printing medium.
As a consequence, in comparison with the known ink jet system, a large number of small-sized fluid droplets can be produced, and also a total number of fluid droplets produced in response to the heating energy corresponding to the recording information, and supplied to the recording fluid heating unit, can be freely controlled in this recording apparatus. Therefore, the multi-level density gradation can be obtained, so that the resulting image quality substantially equal to that of the silver halide recording system can be realized (for instance, full color image).
Also, since this recording system utilizes the vaporization, or sublimation of the dye, the dye accepting layer of the printing medium is no longer heated (conversely, this dye accepting layer should be heated in conventional thermoelectric system). Moreover, both the ink sheet and the printing medium need not be depressed under high pressure. No ink sheet (or ink ribbon) is required. As to this point, there are various merits that the printer can be made compact and in light weight, and also the waste articles can be decreased. Then, since the dye layer of the vaporizing unit is not made in contact with the printing medium, there is no risk that the color mixtures which occur due to the above-explained thermal melting phenomenon, and reverse transfer operation. Even when compatibility between the dye and the dye accepting layer is low, the recording operation ca be done. As a result, varieties of designing and selecting the dyes and the dye accepting layer resins can be widened.
Also, any types of transfer dyes suitable to this recording system may be employed if these transfer dyes own the proper vaporization speed, or the ablation speed, and represent the flowing conditions at a temperature lower than 200xc2x0 C. under a single dye state, or a mixtured dye state, and further the sufficiently high heat resistance characteristic. Concretely speaking, there are disperse dyes, solvent dyes, basic dyes, and acid dyes. Even when such a dye having a melting point higher than the room temperature is employed, this melting point is lowered by mixing the dyes with each other, or mixing the dye with a volatile substance having a low molecular weight.
Also, any types of printing papers suitable to this recording system may be used if these printing papers own the suitable co-melting characteristic with the transfer dye, are capable easily accepting the transfer dye to emphasize the original color of the transfer dye, and also own the effect to fix the transfer dye. For instance, as to the disperse dye, it is preferable to employ such a printing paper on which a polyester resin, a polyvinyl chloride resin, or an acetate resin is coated, which owns the compatibility with the disperse dye. There is another fixing method by which the image transferred to the printing paper is heated so as to osmose the dye transferred to the surface of this printing paper inside the accepting layer.
As described above, this thermoelectric recording system owns the various features such as compactness, easy maintenance, instantaneous imaging operation, images with high image qualities, and high gradation.
Furthermore, the Inventors of the present invention have proposed the compact heating vaporizing type printer with light weight without requiring an ink ribbon while maintaining the above-described merits of the thermoelectric recording system (see Japanese Laid-open Patent Application No. 7-89108).
This prior patent application is directed to such a printer comprised of the dye storing unit for storing the solid-state vaporizable dye, and the fluid vaporizable dye conducting unit for heating the solid-state vaporizable dye stored in this dye storage unit to produce the dye fluid, and for conducting the dye fluid to a plurality of vaporizing units while maintaining the temperature thereof. Then, the fluid vaporizable dyes conducted to the respective vaporizing units are heated/vaporized so as to be thermally transferred to the printing paper. Further, this printer owns at least one heating means for heating the solid-state vaporizable dye to produce the dye fluid and for maintaining the temperature of this dye fluid, and another heating means for heating/vaporizing the dye. In particular, the above-described heating means is suitable for a heater used to supply electric power. As described above, the heater is employed as the heat source instead of the above laser light, so that the manufacturing cost of this printer can be reduced.
On the other hand, for instance, in the printer used to the line type recording system, the recording head having the length corresponding to the width of the recording paper is required. There is a merit in view of the manufacturing aspect that such a long recording head may be constituted by arranging a plurality of recording head portions with the same module structures (for instance, serial type recording head) along a straight line, so as to function as a single recording head.
In the above-described case that a plurality of recording head portions are arranged on a straight line, in order to produce such an image having high resolution, high recording density, and better gradation, the pitch of the recording material heating unit, or the vaporizing unit within the each of the recording head portions in unit of recording operation must be correctly maintained even in the joint portions among the recording head portions.
In the above-described recording head of the prior patent application, when the dyes are fixed on the printing medium to form the dots, the intervals among the respective dye jetting units (heating units, or transfer units) constitute the dot intervals. In other words, a single dye jetting unit corresponds to one dot, and the dot intervals may give a great influence to the resolution of the printed image. If the dot interval is narrow, then the high resolution can be achieved.
As explained above, to realize the high image resolution, it is one of the important aspects to narrow the intervals among the respective dye jetting units. However, in the above recording head, since the dye is supplied from one dye jetting unit to one dye supply path, narrowing the intervals among the respective dye jetting units so as to realize such a high resolution image can narrow the intervals among the respective dye supply paths.
To this end, if the sectional areas of the dye supply paths are not reduced, then it is difficult to narrow the intervals. However, in this case, the fluid flow areas of the dye supply paths are narrowed, so that there is a risk that a sufficient large amount of dyes could not be supplied to the dye jetting units. In addition, the manufacturing methods of the recording heads as well as the dye supply units would become complex, and further the higher manufacturing precision would be required, resulting in lowering of the manufacturing yield, and increasing of the manufacturing cost.
As previously explained, in these recording heads, a portion of the dyes held in the dye jetting unit is vaporized by selectively applying the head amount corresponding to the recording information to this dye jetting unit, and very small vaporized dye gas, or dye fluid droplets are produced in response to the recording information and then are jetted transferred to the printing medium. It could be recognized that the very small dye droplets which are vaporized and then jetted are moved while being dispersed in response to the jetting distances.
As a result, when the distance between the printing medium and the dye jetting unit of the recording head during the printing operation, the resolution of the image to be transferred is readily changed. As a consequence, in order to produce the image having the high resolution on the printing medium, the dye jetting unit must be located very close to the printing medium, and further the interval between these members must be kept constant. However, the above-explained recording heads have no useful measures capable of positioning these members at very close location and of maintaining a constant interval.
Also, in such a case that the recording head is arranged in such a manner that the dyes are jetted upwardly to be transferred to the printing medium, there are some risks that a sufficient large amount of vaporized/jetted dyes could not be reached to this printing medium. This causes the optical density not to be increased. This reason is given as follows. That is, when the vaporized dyes are jetted upwardly over several micrometers, these vaporized dyes are rapidly cooled by ambient air to thereby be condensed. Then, the condensed dyes are easily dropped on the dye jetting unit and the peripheral portions thereof.
An object of the present invention is to provide such a recording apparatus capable of producing an image having sufficient optical density, high resolution, high gradation, and a high image quality without any fluctuation, while maintaining the features of the above-described thermoelectric recording system.
Another object of the present invention is to provide a recording apparatus capable of supplying a sufficiently large amount of recording materials to a recording solution jetting unit, and also capable of easily realizing high resolution in low cost.
The present invention has been made to solve the above-described problems, and therefore owns a further object to provide a recording apparatus capable of increasing a transfer efficiency of the above-explained jetted recording materials, capable of improving transfer density in high resolution, and moreover capable of producing a recorded image with a high image quality and superior gradation.
A recording apparatus, according to one aspect of the present invention, is comprised of a recording head having a plurality of recording head portions (for instance, a heater chip 1 will be discussed later). The recording head portion is arranged by that in a plurality of recording material transporting portion, the recording materials are heated and the heated recording materials are transported to a printing medium. In this recording head, these recording head portions are arranged opposite to each other. In each of these plural recording head portions, the recording material transporting portion includes heating portions for heating the recording materials. As to each of these heating portions a first electrode (e.g., return electrode 41B) and a second electrode (e.g., separate electrode 41A), which are used to energize this heating portion, are positioned opposite to each other. The first electrode among the first and second electrodes is positioned between the plural heating portions. Only the second electrode among the first and second electrodes is present at an opposite end portion between the plural recording head portions.
The above expression xe2x80x9cselectively transported to printing mediumxe2x80x9d implies the following transport operations. That is, the recording material is transported from one recording material transporting portion selected from a plurality of recording material transporting portions to the printing medium; the recording materials are transported from all of the recording material transporting portions to the printing medium; and also the recording materials are transported from any of these recording material transporting portions to the printing medium. Also, the above-described xe2x80x9crecording apparatusxe2x80x9d implies not only printer head made of the above recording heads, but also a printer assembled with this printer head.
The recording apparatus, according to the present invention, is preferably arranged by that the first electrode and the second electrode are arranged in parallel to each other; the first electrode is conducted from one end side of the heating portion; and the second electrode is conducted from the other end side.
The recording apparatus, according to the present invention, is preferably arranged by that the second electrode is a separate electrode connected to a drive circuit unit; and the first electrode is a common electrode for the respective heating portions.
In the above-described recording apparatus, the first electrodes functioning as a common electrode are mutually coupled to one ends of the respective heating portions, and are branched from this coupling portion.
The recording apparatus, according to the present invention, is preferably arranged by that the heating portion is made of a thin-film heating member.
The recording apparatus, according to the present invention, is preferably arranged by that both the plurality of recording head portions, and a printed circuit board for connecting a drive circuit element (e.g., IC chip 16) of the second electrode and the first electrode to an external circuit are fixed to a common base.
Furthermore, the recording apparatus, according to the present invention, is preferably arranged by that the recording apparatus is arranged in such a manner that the heated recording material is transported to the printing medium which is located opposite to the recording material transporting unit under non-contact state.
In the above-described recording apparatus, the recording apparatus is arranged in such a manner that a recording material is vaporized; or ablated by the heating portion, and then the vaporized, or ablated recording material is jetted to the printing medium.
The Inventors of the present invention have executed various experiments and deep research so as to invent more effective structures capable of narrowing intervals among a plurality of dye jetting portions without reducing sectional areas of recording material supply paths. Finally, the Inventors could invent the following recording apparatus.
That is, a recording apparatus, according to another aspect of the present invention, is comprised of a recording head positioned opposite to a printing medium; wherein: the recording head includes: a recording solution jetting portion for jetting a recording solution to the printing medium; a common recording material supply path used to supply the recording material; and a plurality of branch paths branched from the common recording material supply path, for supplying the recording material to the recording material jetting portion; and at least one of the plural branch paths supplies the recording materials to the plurality of recording material jetting portions at the same time. In this case, the term xe2x80x9crecording apparatusxe2x80x9d covers not only a printer head (will be explained later), but also a printer assembled with this printer head.
In the recording apparatus, according to the present invention, is preferably arranged by that the common recording material supply path is formed between a main body of the recording head and a cover portion provided on the main body; and the branch paths are formed partition walls arranged between the main body of the recording head and the cover portion.
The recording apparatus, according to the present invention, is preferably arranged by that the partition wall is formed as a sheet shape; and the branch path between these partition walls is formed as a slit shape.
The recording apparatus, according to the present invention, is preferably arranged by that the plurality of branch walls branched from the common recording material supply path are mutually communicated with each other in a region of the recording material jetting portion.
The recording apparatus, according to the present invention, is preferably arranged by that a recording solution leakage preventing means is provided at a position near the recording material jetting portion, and on the opposite side to the branch path with respect to the recording material jetting portion. For instance, this recording material leakage preventing means is made of volatile oil paint.
The recording apparatus, according to the present invention, is preferably arranged by that a heating means for heating the recording material to jet the heated recording material is provided on the recording material jetting portion. For example, this heating means is constituted by a high resistance material, and one pair of electrodes capable of energizing the high resistance material.
In this case, the high resistance member and the one pair of electrodes are provided on a surface of the main body of the recording head under the partition wall. For instance, one pair of these electrodes are conducted to one end portion of the main body of the recording head, and one of the conducted portions is connected to a recording head drive circuit. For example, both the main body of the recording head, and a printed circuit board containing a recording head drive circuit unit are fixed to a base member.
Also, the recording material jetting portion preferably contains a porous structural body.
Also, the main body of the recording head preferably has a recording solution storage portion for supplying a recording solution to the common recording material supply path.
Also, a recording solution supply tube may be alternatively provided between the recording material storage portion and the main body of the recording head; and the recording material is supplied via the recording material supply tube to the common recording material supply path.
The recording apparatus, according to the present invention, is preferably arranged by that the recording material is vaporized, or ablated, and then the vaporized, or ablated recording material is jetted to the printing medium which is arranged opposite to the recording material jetting portion under non-contact state.
The Inventors of the present invention have executed various experiments and various research so as to invent more effective means capable of maintaining an interval between a recording solution jetting portion and a printing medium in a recording apparatus.
In other words, a recording apparatus, according to another aspect of the present invention, is arranged by that a recording head positioned opposite to a printing medium is comprised of a recording solution jetting portion for jetting a recording solution to the printing medium; the recording head is relatively inclined with respect to the printing medium to be made in contact with the printing medium; and the recording material jetting portion and the printing medium are arranged in such a manner that a predetermined interval between the recording material jetting portion and the printing medium is kept by the contact made between the recording head and the printing medium. In this case, the term xe2x80x9crecording apparatusxe2x80x9d covers not only a printer head (will be explained later), but also a printer assembled with this printer head.
In the recording apparatus, according to the present invention, is preferably arranged by that the recording head is made in contact with the printing medium at a predetermined inclination angle with respect to the printing medium on the side of the recording material jetting portion.
The recording apparatus, according to the present invention, is preferably arranged by that the recording head is made in contact with the printing medium in such a manner that an interval between the recording head and the printing medium is gradually narrowed toward the recording material jetting portion.
The recording apparatus, according to the present invention, is preferably arranged by that the interval between the recording head and the printing medium is increased on the side where the recording head is positioned opposite to the printing medium while the recording head is separated from the contact position between the recording head and the printing medium to the opposite side with respect to the recording material jetting portion.
Also, the recording head is preferably, relatively slid with respect to the printing medium. For example, the recording material jetting portion of the recording head is positioned downwardly, opposite to the printing medium so as to carry out the recording operation by the recording head.
Then, the recording head preferably includes: a common recording material supply path for supplying the recording material; and a branch path branched from the common recording material supply path, for supplying the recording material to the recording material jetting portion.
In this case, the common recording material supply path is formed between a main body of the recording head and a cover portion provided with the main body; a plurality of partition walls are provided between the main body of the recording head and the cover portion; and branch paths are formed among the partition walls.
Also, a heating means for heating the recording material to jet the heated recording material is provided on the recording material jetting portion. For instance, the heating means is constituted by a high resistance material, and one pair of electrodes capable of energizing the high resistance material.
In this case, the high resistance member and one pair of electrodes are provided on a surface of the main body of the recording head under the partition wall. For example, one pair of these electrodes are conducted to one end portion of the main body of the recording head, and one of the conducted portions is connected to a recording head drive circuit.
In this case, both the main body of the recording head, and a printed circuit board containing a recording head drive circuit unit are fixed to a base member.
Further, this recording material jetting portion preferably contains a porous structural body.
Also, the main body of the recording head has a recording solution storage portion for supplying a recording solution to the common recording material supply path.
Alternatively, a recording solution supply tube may be provided between the recording material storage portion and the main body of the recording head; and the recording material may be supplied via the recording material supply tube to the common recording material supply path.
Also, the recording apparatus, according to the present invention, is preferably arranged by that the recording material is vaporized, or ablated, and then the vaporized, or ablated recording material is jetted to the printing medium which is arranged opposite to the recording material jetting portion under non-contact state.